1. Field of the Invention
The present invention relates to a photo-coupler semiconductor device in which semiconductor light emitters and semiconductors light detectors are coupled optically with each other and a method of manufacturing the same.
2. Description of the Prior Art
Today, a photo-coupler semiconductor device (hereinafter referred simply to as photo-coupler), comprising a semiconductor light emitter and a semiconductor light detector coupled with each other optically, has been viewed as a new solid state device and is widely used for solid state relays and transmission lines as an isolation element. Especially, it has been seen that a photo-coupler array, having a plurality of photo-couplers arranged on a substate in parallel relation, and a combination circuit device of photo-couplers and integrated circuits have an extremely effective application to logic circuits or telephonic circuits.
In manufacturing a photo-coupler, the following points must be taken into consideration; (1) in increase in the dielectric breakdown voltage between the light emitter and the light detector by maintaining more than about 100 .mu.m spacing therebetween and the prevention of erroneous operations due to electrostatic coupling be decreasing the electrostatic capacitance between the light emitter and the light detector; and (2) the prevention of erroneous operations due to stray light and an improvement in the light transmission efficiency between the light emitter and the light detector by focussing light emitted from the light emitter to assure a converged irradiation upon a light sensitive region of the light detector.
Hitherto, a photo-coupler satisfying the above-mentioned requirements has not been devised. One example of known photo-couplers comprises a light emitter and a light detector with opposing surfaces facing each other, on which a light emitting region and a light sensing region are provided respectively, and a transparent resin or glass interposed at an interface between the regions. With this construction, since the resin or glass extends over the entire area of the opposing surfaces of the light emitter and of the light detector, light emitted from the light emitter irradiates not only the highly photosensitive region of the light detector but also the remaining area of the surface facing the light emitter, with the result that the quantity of light incident on the light sensing region is decreased and the light transmission efficiency is impaired. To eliminate these drawbacks, an expedient has been proposed wherein, at the interface between the opposing surfaces of the light emitter and the light detector, there is interposed resin or glass along with a metal block which restricts the expansion of the resion or glass to a desired area of the light detector. However, in manufacturing photo-coupler arrays or integrated circuits with photo-couplers, the area of the light sensing region of the light detector undergoes a limitation to a maximum of about 100 .times.100 .mu.m to satisfy the need for highly concentrated integration. The use of the metal block made in such case suffers from extreme ficulties in the accurate alignment of the metal mold with the light emitter and the light detector, giving rise to a fatal cause for impairing the yield rate of the mass production of photo-couplers.